Home > the mind, work > Meth and the brain (notes)

Meth and the brain (notes)

rough notes for my education group. People were into the presentation even non-Meth users. I was surprised by how many had tried it. Next week we take on crack.

Wikipedia: Methamphetamine is a potent central nervous system stimulant that affects neurochemical mechanisms responsible for regulating heart rate, body temperature, blood pressure, appetite, attention, mood and responses associated with alertness or alarm conditions. The acute physical effects of the drug closely resemble the physiological and psychological effects of an epinepherine-provoked fight, flight or freeze, including increased heart rate and blood pressure, vasoconstriction (constriction of the arterial walls), bronchodilation, and hyperglycemia (increased blood sugar). Users experience an increase in focus, increased mental alertness, and the elimination of fatigue, as well as a decrease in appetite.

Methamphetamine is a potent neurotoxin, shown to cause dopaminergic degeneration. High doses of methamphetamine produce losses in several markers of brain dopamine and serotonin neurons. Dopamine and serotonin concentrations, dopamine and 5HT uptake sites, and tyrosine and tryptophan hydroxylase activities are reduced after the administration of methamphetamine. It has been proposed that dopamine plays a role in methamphetamine-induced neurotoxicity because experiments that reduce dopamine production or block the release of dopamine decrease the toxic effects of methamphetamine administration. When dopamine breaks down it produces reactive oxygen species such as hydrogen peroxide.

Physical effects can include anorexia, hyperactivity, dilated pupils, flushing, restlessness, dry mouth, headache, tachycardia, bradycardia, tachypnia, hypertension, hypotension, hyperthermia, diaphoreses, diarrhea, constipation, blurred vision, dizziness, twitching, insomnia, numbness, palpitations, arrhythmias, tremors, dry and/or itchy skin,acne,pallor, and with chronic and/or high doses, convulsions, heart attack, stroke, and death can occur.

Psychological effects

Psychological effects can include euphoria, anxiety, increased libido, alertness, concentration, energy, self-esteem, self-confidence, sociability, irritability, aggression, psychosomatic disorders, psychomotor agitation, hubris, excessive feelings of power and invincibility, repetitive and obsessive behaviors, paranoia, and with chronic and/or high doses, amphetamine psychosis can occur.

Withdrawal effects

Withdrawal is characterized by excessive sleeping, increased appetite and depression, often accompanied by anxiety and drug-craving.

Short-term tolerance can be caused by depleted levels of neurotransmitters within the synaptic vesicles available for release into the synaptic cleft following subsequent reuse (tachyphylaxis). Short-term tolerance typically lasts until neurotransmitter levels are fully replenished; because of the toxic effects on dopaminergic neurons, this can be greater than 2–3 days. Prolonged overstimulation of dopamine receptors caused by methamphetamine may eventually cause the receptors to downregulate in order to compensate for increased levels of dopamine within the synaptic cleft. To compensate, larger quantities of the drug are needed in order to achieve the same level of effects.

Methamphetamine is addictive. While not dangerous, withdrawal symptoms are common with heavy use and relapse is common. Methamphetamine use causes hyperstimulation of pleasure pathways which leads to anhedonia. It is possible that daily administration of the amino acids L-Tyrosine and L-5HTP/Tryptophan can aid in the recovery process by making it easier for the body to reverse the depletion of dopamine, norepinephrine, and serotonin. The mental depression associated with methamphetamine withdrawal is longer lasting and more severe than that of  cocaine withdrawal.

ScienceDaily (Mar. 28, 2000) —In an article published in the March 28 issue of Neurology, scientists at the Harbor-UCLA Medical Center in Torrance, California, used magnetic resonance spectroscopy to take measurements of three parts of the brains of 26 participants who had used methamphetamine and then compared them with measurements of the same regions in the brains of 24 people who had no history of drug abuse.

“the meth users in this study hadn’t used the drug for some time–anywhere from two weeks to 21 months, this research strongly suggests that methamphetamine abuse causes harmful physical changes in the brain that can last for many months and perhaps longer after drug use has stopped,” In their study, Dr. Linda Chang and Dr. Thomas Ernst measured levels of brain chemicals that indicate whether brain cells are healthy or are diseased or damaged.

“We found abnormal brain chemistry in the methamphetamine users in all three brain regions we studied. In one of the regions, the amount of damage is also related to the history of drug use–those who had used the most methamphetamine had the strongest indications of cell damage,” Dr. Chang said.

The researchers found that levels of one chemical marker, N-acetyl-aspartate, were reduced by at least five percent in the methamphetamine abusers. “Many diseases associated with brain cell loss or damage, such as Alzheimer’s disease, stroke, and epilepsy, are also associated with reduced N-acetyl-aspartate,” said Dr. Ernst. “Reduced concentrations of N-acetyl-aspartate in the drug users’ brains suggest that long-term methamphetamine abuse results in loss or damage to neurons, the cells we use in thinking.” Two other chemical markers, myo-inositol and choline-containing compounds, are associated with glial cells, which act to support neurons. “Methamphetamine abusers showed increases of 11 percent and 13 percent in levels of these markers compared with normal individuals,” Dr. Ernst said. “This suggests an increased number or size of glial cells as a reaction to the injurious effects of methamphetamine.”

Abstinence Can Reverse Some Brain Damage

From JAMA News Release

Updated April 08, 2005

Adaptive changes in chemical activity in certain regions of the brain of former methamphetamine users who have not used the drug for a year or more suggest some recovery of neuronal structure and function, according to an article in the April 2005 issue of Archives of General Psychiatry, one of the JAMA Archives journals.

Methamphetamine use has been shown to cause abnormalities in brain regions associated with selective attention and regions associated with memory, according to background information in the article. Recent animal and human studies suggest that neuronal changes associated with long-term methamphetamine use may not be permanent but may partially recover with prolonged abstinence.

Thomas E. Nordahl, M.D., Ph.D., of the University of California, Davis, and colleagues compared eight methamphetamine users who had not used methamphetamine for one to five years and 16 recently abstinent methamphetamine users who had not used the drug for one to six months with 13 healthy, non-substance-using controls using a method of brain imaging, proton magnetic resonance spectroscopy (MRS), that allows the visualization of biochemical markers that are linked with damage and recovery to the neurons in the brain.

The researchers measured biomarkers in the anterior cingulum cortex, a region of the brain associated with selective attention. Levels of N-acetylaspartate (NAA), which is present only in neurons, were measured as a marker of the amount of damage (neuronal loss). Choline (Cho), which is generated by the creation of new membranes and, the authors write, “may be an ideal marker to track changes consistent with neuronal recovery associated with drug abstinence,” was measured as a biomarker of recovery.

Levels of NAA were abnormally low in all the methamphetamine users, the authors found. Levels were lower relative to the length of methamphetamine use, but did not change relative to the amount of time that the methamphetamine users had been abstinent. The researchers found elevated Cho levels in the methamphetamine users who had not used the drug in one to six months, but normalized levels in the longer abstainers.

Normalization of Function

“In the early periods following methamphetamine exposure, the brain may undergo several processes leading to increased membrane turnover. The relative Cho normalization across periods of abstinence suggests that when drug exposure is terminated, adaptive changes occur, which may contribute to some degree of normalization of neuronal structure and function,”

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